On Mon, 26 Mar 2012 21:39:52 +1100, Noddy wrote:

Hi All,

I'm a long term lurker but first time poster and I have a question about
Bridgeport heads that I'm hoping someone might be able to help with.

In my home shop I have a Korean stepped pulley Bridgeport clone that was
made in the mid 80's and looks identical to an original Series I
Bridgeport. It's a great machine that was reconditioned a couple of
years ago, and so close in appearance to an original Bridgeport does it
appear to be that original Bridgeport parts were used to refurbish the
head without any problems.

A couple of months ago a friend gave me a variable speed Series II head
that came out of a large production factory where he works. It was
apparently an accessory for a large Bridgeport horizontal mill that was
being scrapped, and as far as I'm aware this variable speed head has
done very little over the years other than sitting around getting
incredibly dirty.

I'd like to replace the old stepped pulley head on my machine with the
Series II head, but the problem for me is the spindles. The Series II
head has a standard R8 taper while my clone has an ISO 30 taper and
changing to the Series II head will obviously mean none of my current
tooling will be suitable.

Of course, I could just bolt the Series II head on and buy some new
tooling, but I've collected quite a bit of ISO 30 stuff over the years
and replacing it all would be costly. I also wish to avoid adapters as
they can make life complicated.

What I was wondering is how interchangeable are the top and bottom
halves of Series I & II Bridgeport heads?

What I was thinking is that if I could transplant the variable speed top
half of the Series II head onto the bottom half of the old stepped
pulley head I'd kill a couple of birds with one stone in that I'd retain
the use of all my tooling and benefit from the new bearings that were
fitted to the old head not long ago and that have not done much since.

I appreciate that the old machine isn't a genuine Bridgeport and there
may be problems associated with that, but what I was hoping to find out
was that assuming for a moment that the old head was identical to a
Bridgeport stepped pulley head would such a swap be possible?

Any help would be greatly appreciated,
As I recall the spindles are interchangeable. Maybe not always the
quill though. The quills, I have been told, were individually fit
into the heads. I don't know how true this is. But if your machine is
an exact copy of a Bridgeport then measure the O.D. of the quill and
see if it's the same as the Bridgeport quill. If they are the same
then using this link:
http://home.comcast.net/~tom.jelly/j...%20rebuild.htm
you should be able to swap quills pretty easily. If the quills do
differ substantially then swapping spindles will probably work.
Eric